This invention is concerned with improvements in or relating to shoe machines, more especially with methods of and apparatuses for compensating for defects in clamping shoes or shoe components which are placed in a shoe machine, wherein a shoe treatment tool, e.g. an adhesive applicator nozzle, is moved automatically relative to the shoe or component to be treated along an operating path determined by longitudinal and transverse coordinates by means of a control device storing the coordinates, the lateral relative position of the operating path to the shoe or shoe component being determined by a measured dimension sensed on the clamped shoe or component.
One such method is described in DE-C No. 3341118 in association with a cement toe and side lasting machine wherein, it will be appreciated where shoes loaded by hand may be subject to a certain lateral offset from the optimum position. In order to avoid compensating for this by undesired adjustment operations, it is proposed in said specification to progressively sense the periphery of the shoe using a feeler, as the tool, viz. adhesive applicator nozzle is moved longitudinally along the shoe bottom. Furthermore in such case it is considered advantageous to sense the periphery of the outer side of the shoe, where the periphery is relatively sharply defined, rather than of the inner side of the shoe where, because of the sharply reentrant irregular shape of the last, the shoe is unsuitable for sensing. The result of this sensing of the outside of the shoe is then combined in the control device with the particular stored transverse coordinates for the operating path along the inside of the shoe in such a manner that this path can be correspondingly corrected continuously during the longitudinal movement of the tool. In addition, the result of the sensing is compared with the stored transverse coordinates for the operating path along the outside of the shoe and the thus imparted differential value is arrived at for calculating the correction of the operating path along the inside of the shoe.
For implementing the above-described method, viz. for the transverse movement of the adhesive applicator nozzle which runs along the inner periphery of the shoe an appropriate apparatus is used which comprises a servomotor supported opposite the feeler sensing the outer periphery of the shoe, whereby an initial position given by the corresponding disposition of the feeler is supplied to the servomotor. The servomotor must then, in the case of a shoe region the width of which is increasing, e.g. in the direction of the toe to the ball, compensate for a path length which takes into account both the outwardly directed movement of the feeler and also the outwardly directed movement of the inner adhesive nozzle opposing it. This inner adhesive nozzle is to some extent drawn by the feeler in the wrong direction, which must be compensated for by a correspondingly quicker operation of the servomotor. This leads, in the case of fast movements of the nozzles in the sense of a fast execution of the operation, to significant acceleration forces to which the feeler is subjected, since the servomotor is arranged to be supported for these movements opposite the feeler. These forces can be accommodated only if the feeler engages the outer periphery of the shoe under a relatively high pressure.
The sensing of the outer periphery of the shoe by means of a feeler is made difficult if the adhesive nozzles are to be effective in a region which is covered laterally by pulling over pincers, as are necessary for toe lasting. In this case the pulling over pincers or, as the case may be, the upper tensioned by them over the insole edge prevent the feeler from properly engaging the shoe and thus its movement along the outer periphery of the shoe. Furthermore, the feeler, which is to be continuously moved, requires a guide which extends over the length of the shoe being operated upon, giving rise to further constructional requirements.
It is the object of the present invention to determine and compensate, in an especially simple and above all speedy manner, for defects in the clamping of shoes.